"It would be a step in the wrong direction to force currently serving transgender individuals to leave the military solely on the basis of their gender identity rather than medical and readiness standards that should always be at the heart of Department of Defense personnel policy," McCain said.

"The Pentagon's ongoing study on this issue should be completed before any decisions are made with regard to accession. The Senate Armed Services Committee will continue to conduct oversight on this important issue."

McCain, a former Navy pilot who spent more than five years as a prisoner of war during the Vietnam War, chairs the Senate Armed Services Committee.

After Trump first announced the ban on transgender troops serving the military last month, McCain said unveiling a policy without first conducting a study is inappropriate.

Forcing transgender soldiers out of the military is the wrong move, Sen. John McCain, R-Ariz., said Friday. McCain responded to President Donald Trump's order that prevents the military from accepting new transgender troops in a statement from his office.